211231021 has 4 divisors (see below), whose sum is σ = 211263552. Its totient is φ = 211198492.

The previous prime is 211230997. The next prime is 211231049. The reversal of 211231021 is 120132112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 211231021 - 2¹⁷ = 211099949 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 211230992 and 211231010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211231051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2821 + ... + 20746.

It is an arithmetic number, because the mean of its divisors is an integer number (52815888).

Almost surely, 2^211231021 is an apocalyptic number.

It is an amenable number.

211231021 is a deficient number, since it is larger than the sum of its proper divisors (32531).

211231021 is an equidigital number, since it uses as much as digits as its factorization.

211231021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32530.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 211231021 is about 14533.7889416353. The cubic root of 211231021 is about 595.5513764695.

Adding to 211231021 its reverse (120132112), we get a palindrome (331363133).

It can be divided in two parts, 2112 and 31021, that added together give a palindrome (33133).

The spelling of 211231021 in words is "two hundred eleven million, two hundred thirty-one thousand, twenty-one".